I am seeing a lot more people apply to our guild after the new patch. Some are from players that want to break into raiding, and some are from guilds that fell apart after Naxx boredom/Ulduar shock killed their guild.
There are only so many players a raiding guild can comfortably handle before they become too many or not enough. I use a sponge as an analogy. If the sponge doesn't have enough water for a long enough time, it becomes dry and cracks; a guild like this will most likely split off into several directions/new guilds. If a guild has too much water, the excess simply falls away from it; players not being utilized in the raid will quit and find other guilds that can better utilize them.
It seems to me that on my server there aren't enough jobs for people that want to raid the new content. Well, not exactly that, but there are people leftover that want to raid, but can't find a spot to do so; simultaneously there isn't enough critical mass in the leftover raiders to organize a new group of players to fill an entire raid.
People seem to be still stuck in the BC mentality that raiding = 25man. Ten man raiding is thriving and is at a better place than ever it seems, but if I was a 10man raider it would eventually go dry and I would want to go back to the 25man stuff. It seems that it would not take much effort to start raiding 10 man stuff, and eventually merging guilds to get into 25 mans again;that transition is sometimes such a shock that some guilds don't survive it.
4 hours ago